Conformational Dependence of Triton X-100 on Environment Studied by 2D NOESY and ¹H NMR Relaxation

Abstract

Conformation of Triton X-100 (TX-100) in the bulk and in aqueous solutions at concentrations higher and lower than the critical micellar concentration (cmc) was studied by NMR relaxation, two-dimensional nuclear Overhauser enhancement spectroscopy (2D NOESY), and molecular simulation by HYPERCHEM. Results show that motion of TX-100 in dilute solution (0.5 cmc) is in the extreme narrowing condition. Molecules are in the single molecular state with an extended polyoxyethylene chain. In forming micelles, these hydrophilic polyoxyethylene chains, staying in the exterior of the micellar core, coil, bend, and align along the surface of the TX-100 micellar core, forming a layer thick in dimension and loose in structure around the micellar core with a certain number of water molecules included. This hydrophilic layer is in contact with the solvent, water, keeping the micellar solution stable. The micelle is spherical at 10 cmc. Motions of all of the protons of TX-100 in the bulk, even of those on the polyoxyethylene chain, are more restricted than motions of those in the micellar core. Exponential decay of the proton spin-spin relaxation of TX-100 in the bulk shows the absence of oriented self-aggregation. Very short internuclear distances of the protons between hydrophilic and hydrophobic parts of TX-100 bulk measured from the 2D NOESY spectrum show that the molecules are arranged randomly, closely, and uniformly, which is the origin for the high viscosity of TX-100 bulk. Results are discussed in terms of inter-and intramolecular interactions.

Unusual, pH-Induced, Self-Assembly Of Sophorolipid Biosurfactants

“…Cross-signals in a NOESY spectrum rely on the cross-relaxation of longitudinal magnetization during a selected mixing time. 2D NOESY is currently employed to characterize internuclear distances and molecular conformation in surfactants micellar systems 47,48 and it will be employed here to probe proton-proton proximities within SL; in particular, we will focus on the interactions involving the COOH group but one should recall that it is not possible to distinguish between intramolecular and intermolecular interactions. NOESY experiments.…”

Investigating the Location of Propyl Gallate at Surfaces and Its Chemical Microenvironment by 1H NMR

“…A number of techniques were found to be suitable to investigate solubilization properties [23]. Using spectroscopic methods like different NMR techniques, quantitative measurements of the interactions between emulsifier and solute are possible [19,22,24,25]. T 1 relaxation measurements give direct information about interactions with the chemical environment due to the transfer of energy from the spin system to the medium [26][27][28].…”

1H NMR Study of Mixed Micellization of Sodium Dodecyl Sulfate and Triton X-100

“…They form a shell, thick in space, surround- ing the hydrophobic micellar core as evident by the existence of cross peaks between the hydrophilic oxyethylene protons (T-5) and the remote protons in the micellar core (T-6, T-7, and T-8) (29). From Fig.…”